From the Guidelines
Four hourly aspirates in a Ryles tube are essential to monitor gastric residual volume and assess gastric emptying in patients receiving enteral feeding, as recommended by the guidelines for enteral feeding in adult hospital patients 1. The procedure involves withdrawing stomach contents through the nasogastric tube every four hours to check how much undigested feed remains in the stomach.
- The recommended practice is to gently aspirate using a 50ml syringe, measure the volume obtained, and document the findings.
- If the aspirate volume exceeds 200ml, feeding may need to be temporarily held or the rate reduced to prevent complications, as suggested by the guidelines 1. This monitoring is crucial because high residual volumes can indicate delayed gastric emptying, which increases the risk of regurgitation and aspiration pneumonia.
- The aspirate should also be checked for color and consistency, as unusual characteristics (such as coffee-ground appearance) might indicate bleeding or other complications. Regular aspirate checks help ensure safe enteral feeding, optimize nutritional delivery, and reduce complications in patients who cannot eat normally. The four-hour interval provides an appropriate balance between adequate monitoring and allowing sufficient time for gastric emptying, and is supported by the most recent and highest quality study available 1.
From the Research
Gastric Residual Volume Checks
- The practice of checking gastric residual volumes (GRV) in tube-fed patients is common, but there is a lack of scientific evidence to support this practice 2.
- A survey of nursing practice found a wide variation in the management of GRV, including unnecessary checks and withholding of feedings, which can increase healthcare costs and impact patient outcomes 2.
Frequency of Aspirates
- There is no direct evidence to support the specific practice of taking four hourly aspirates in Ryles tube.
- However, studies have investigated the use of prokinetic agents such as metoclopramide to facilitate gastric emptying and reduce the risk of aspiration pneumonia 3, 4, 5, 6.
- These studies suggest that metoclopramide may be effective in reducing the risk of pneumonia and improving gastric emptying, but the optimal frequency of aspirates is not specified.
Gastric Emptying and Aspiration Pneumonia
- Delayed gastric emptying is a common problem in critically ill patients, and can increase the risk of aspiration pneumonia 3, 5.
- The use of prokinetic agents such as metoclopramide and erythromycin has been shown to improve gastric emptying and reduce the risk of aspiration pneumonia 3, 4, 5.
- However, the optimal strategy for preventing aspiration pneumonia in patients with delayed gastric emptying is not clear, and further research is needed to determine the best approach.